This invention relates to a combined transmission systems that transmit input mechanical power into direction output.
For this purpose the are two main system available in previous art:
Mechanical oscillating energy transmits to the input, and than transmission device provides a unidirectional energy to the output. PA1 Continues unidirectional mechanical energy transmits to the input and transmission device changes speed to output. We can make analogy with electrical energy, where two sources of energy: direct and alternative current available, but electric motor using this energy, has unidirectional motion.
In transmitting oscillation energy the prior art transmissions have not successfully transmitted high torque levels. One common type of transmission device is a one-way clutch. In these known systems: such as in U.S. Pat. No. 5,333,517 by Rodney Bryson, Aug. 2, 1994, rollers or other drive members are engaged within notches or openings in a driven member. The rollers engage and move the driven member when rotation is transmitted in a first direction, but will slip when rotation is transmitted in a second direction. The invention disclosed in U.S. Pat. No. 5,333,517 has a ratio between the worm and worm gear of 5, however, the number of threads on the worm is more than one, and the worm does not have a self locking feature. These types of clutches have enjoyed wide usage, but have been unable to transmit high torque loads. One proposal suggests using a pair of such clutches with an oscillating input to perform as a part of a vehicle transmission. Due to the low torque load, this system would be impractical. A main disadvantage of these types of clutches is a discrete characteristic of changing of contact. It leads to mechanical shocks during every new contact between driving and driven elements. Drive systems for providing speed in a single rotational direction from a reversible input are also well known (U.S. Pat. No. 5,333,517 by Rodney Bryson, Aug. 2, 1994). But this system has a gear train with some backlashes and it is not able to provide small amplitude of vibration. Besides, the input and output shafts are perpendicular to each other, and therefore, this drive system cannot be used in many applications.
In one system disclosed in a Soviet inventor certificate number 1,486,686 (1989) granted to the inventor of this invention, a self-locking transmission is utilized to transmit rotation. In the disclosed system, a worm and a worm gear combination are utilized to transmit rotation. The rotation is transmitted utilizing the engaged teeth and thread of the gears such that there is not relative movement between the two gear members during this rotation. With such a system, many valuable benefits result. In particular, one is able to accurately and efficiently transmit rotation through the self-locking transmission. A main advantage of these types of clutches is continuous contact between the driving and driven elements.
In addition, the standard power supply utilized with such systems has difficulty allowing any of the structure to freely turn about 360 degrees. Instead, electrical supply lines have typically limited the operative members to a restricted range of rotation. This is, of course, undesirable.
In transmitting continues unidirectional energy and change the ratio by using self-locking properties of worm/worm gear transmission in the prior art t are different modifications.
In general, prior art using combinations of strait worm and gear with combinations of differential means.
Examples of these transmissions are in U.S. Pat. No. 2,583,140, to Else; U.S. Pat. Nos. 2,225,957 to Korff, 3,208,305 to Butterbaugh, U.S. Pat. No. 4,346,728 to Harry; U.S. Pat. No. 4,917,200, to Lucius; U.S. Pat. No. 4,346,728, to Sulzer, U.S. Pat. No. 4,987,788 to Bausch; U.S. Pat. No. 4,973,295, to Lee; U.S. Pat. No. Re. 33,278, to Johnshoy; U.S. Pat. No. 3,220,284, to Horvath; U.S. Pat. No. 5,033,996, to Frey; U.S. Pat. No. 5,015,898, to Frey.
To have a self-lock is better to use worm with only one thread, it makes lead angel smaller. In previous art with a strait worm it was possible by making only more than one revolution of the thread. It is why only two worm gear teeth and threads were in a mesh. When total worm gear teeth more than 24 it makes each tooth small and limits load capacity. Minimum ratio in previous art for ratio with one thread is 24, but to able to control motion of the worm its speed became in 24 times greater than speed of the worm gear. It is why previous art was noir realized in any reasonable real transmissions. Increasing size of the worm pitch diameter to make comparable with worm gear pitch diameter was also unpractical, because it makes very small threads relatively to the big body of the worm. Using of standard double enveloping worm/worm gear having more than 24 worm gear teeth and enveloping angle for one revolution of a worm thread less than 15 degree has the same problem: small and weak teeth, high ratio, more 24. Enveloping worm has a middle part and periphery part. The middle part in mesh with worm gear on the top of the worm gear. The periphery part in mesh with the periphery worm gear on the side of the worm gear. To provide self-lock better to increase periphery mesh between worm and worm gear. But standard enveloping worm has only mesh on the top the worm gear. Increasing periphery mesh leads to more than 3 teeth in contact for single thread. But it makes difficult to assemble a worm with a worm gear and still has the same problem.
The term "self-locking" as is utilized in this application to describe the inventive worm and worm gear combination requires that the teeth of the worm gear when in contact with the thread of the worm are incapable of rotating the worm about its axis. By carefully selecting the material of the respective teeth and threads, and the respective angles, a worker of ordinary skill in the art would be able to achieve this goal.
There are some deficiencies in the system disclosed in the prior inventor's certificate, however, and this invention and a parent patent applications of the same inventor, Ser. No. 08/732,150, Filed Oct. 16, 1996 entitled "Worm/Wormgear Transmission And Apparatus For Transmitting Rotating Utilizing An Oscillating Input" and Ser. No. 08/796,466, Filed Feb. 10, 1997 entitled "Apparatus For Transmitting Rotation Utilizing an Oscillating Input" disclose improvements to the prior art systems.